Chloro fluoroform

Alkanoyl chlorides and chloroformates can be treated with potassium fluoride and benzyItriethylammonium chloride to obtain the respective alkanoyl fluorides or fluoroformates [62]. 2-Amino-6-chloro-9-(2,3,5-tri-0-acetyl-P-D-ribofurano-syl)purine is converted to the 2-amino-6-fluoro product with potassium fluoride and trimethylamme in dimethylformamide under rigorously anhydrous conditions [65] (equation 37)... 

Like thallium(I) fluoride (see Section 18.2.), silver(I) tetrafluoroborate is used to convert chloro-formates into the corresponding fluoroformates, which are decomposed to the fluorides as described in Section 16.1.2. Phenyl fluoroformate (4) is obtained in moderate yield in this way from 3.68... 

Chlonne-36-labeled 1,1-dichlorotetrafluoroethane is produced photochemically from chlonne-36 and l-chloro-l,2,2,2-tetrafluoroethane in better than 90% yield [22] Fluoroform is brominated to yield bromotrifluoromethane The reaction rate and yield are both enhanced by various catalysts, as summarized in Table 7 [23, 24, 25]. 

The instability of tert-butyl chioroformate limits its use for preparing Boc derivatives.102 /ert-Butyl fluoroformate (bp 40-42 aC/23.3 kPa)103104 is more stable than the chloro derivative and more reactive than rm-butyl azidoformate (HAZARD). Both reagents should be prepared afresh. rm-Butyl azidoformate (bp 36.5-37.5 °C/1.3 kPa)105 has the added frisson of being explosive hence, it should be prepared in situ from the reaction of Boc-hydrazide with nitrous acid and used without purification. Moreover, the by-product of aqueous workup, hydrazoic acid, is highly toxic. 

Much better results can be obtained with substituted aromatics. The reaction of aryl chloro- or fluoroformates which have alkyl groups in position 2 and 6 gives fluoroaromalic compounds in good yield. The Friedel-Crafts reaction is widely suppressed although Lewis acids or hydrogen fluoride are present in the reaction mixture. Another advantage of this process is that the fluoroaromalic compounds can be obtained from the fluoro- as well as from the chloroformates. which, in general, are easier to prepare, A typical example is the formation of 2-fluoro-1.3-dimethylbenzene (2). ... 

Fluoroformic and chloroformic esters of secondary alcohols may be decarboxylated, thermally or catalytically, to the corresponding fluoro-i or chloro-i i compound. Although 6-0-(chloroformyl)-1,2 3,4-di-O-iso-propylidene-a-D-galactopyranose is converted into 6-chloro-6-deoxy-l, 2 ... 

In enzymatic reactions, SCFs have shown their potential as better alternatives to conventional organic solvents, due to easy product recovery, lower heating requirements, and side reactions. The first attanpt to use SCFs in enzymatic reactions dates to 1985, when an alkaUne phosphatase was used, followed by p-cresol and p-chloro-phonol oxidation with polyphenol oxidase (Hammond et al., 1985). The fluids used in enzymatic reactions are those that have low critical temperatures to avoid the thermal denaturation of the enzyme. Therefore, CO2, ethane, and fluoroform have been the commonly used. Superaitical water, however, cannot be used due to a high critical temperature Q1AA°C), which deactivates the enzyme. On the other hand, it is well known that enzymes, and proteins in general, are not affected by high pressure (Lanza et al., 2004 Prasanth and Abraham, 2009). 

HF reaction with 3-chloro-pentafluoro-l-propene (CF2=CF-CF2C1) at 200°C, catalyzed by activated carbon, yields HFP. l Hexafluoropropylene can be prepared from the catalytic degradation of fluoroform (CHF3) at 800-1000°C in a platinum-lined nickel re-actor.l l Another method is copyrolysis of fluoroform and chlorotrifluoroethylene (CF2=CFCl),f l or chlorodifluoromethane and l-chloro-1,2,2,2-tetrafluoroethane (CHClFCFg), giving good yields of HFP. 

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